I have been rewatching all of DB and DBZ and and recording all recurring character appearances and such. (Why? It helps me pay attention to the boring parts. Also, it could be useful some day.) Dr Brief's cat was initially included as a lark and he/she has been in 11 episodes up to where I am now, DBZ Ep#81/Movie 4.
In English, the cat is apparently named Scratch but I haven't seen much of the English dub. In Japanese, the cat is supposedly named "Tama" according to DBWIKI, but that wiki is notoriously focused on the English dub and video games which isn't really my interest. Having watched all eleven appearances so far, I know the cat isn't named.
EXCEPT in Movie #4, there is a picture that looks to be the same cat on the side of a truck with the name "Tama" next to it. In-universe, it doesn't look to be a Capsule Corp truck, so I don't know what we're supposed to make of that. It's also a fairly generic look for a cat...
So, is this Movie #4 reference the reason for the cat's name? Or was the name revealed in some promotion tie-in at some point and this was a call-back to that? Or did the name get revealed later and ended up in a Daizenshuu or similar?
Do we know the cat's name? Is it "Tama"? And if so, how do we know that?
